Communications that are carried out over a network such as the Internet may be vulnerable to tampering, message forgery, eavesdropping and the like. Secure Shell (“SSH”) is a well-known family of communications protocols that may be used to establish a secure communications link between a pair of computer processing devices such as, for example, a server and a client computer or a pair of servers. The SSH protocols are most commonly used for communications over the Internet, but may be used for communications over any public or private network and, in particular, over networks in which messages are vulnerable to eavesdropping or may otherwise be compromised. The SSH protocols use public and private keys to allow first and second processing devices to authenticate each other without using passwords or otherwise exchanging information in advance. Once authentication is completed, users that are logged onto the first and second processing devices can exchange data over a secure, encrypted communications link. As the SSH protocols can be configured in a way that does not require passwords (which must be stored in, for example, application scripts on at least one of the processing devices), they tend to be more secure than other communications protocols such as the File Transfer Protocol (“FTP”), as stored passwords may not be updated with sufficient frequency and/or may be vulnerable to hacking.
There are at least two known methods for establishing trust between the users of two different systems without the use of passwords. The first such mechanism involves the use of authorized keys. The second mechanism involves the use of certificates that are submitted by the client. Both approaches avoid keeping passwords in application scripts and likewise avoid transmission of password information.